Being mesmerised?

Where does “Being Mesmerised” come from?

You would have thought it would come from Mesmer, Mesmer did create a theory he called “animal magnetism” or “mesmerism” based on magnets to impede bleeding. However, it was James Braid, a Scottish surgeon who discovered that an altered state of consciousness could be induced through the use of visual fixation on a light and called it “mesmerism”. Through later experiments he used the words “neurohypnosis” meaning nervous sleep which later was shortened to hypnosis.

We tend to use the phrase for anyone who is daydreaming, in other words in an altered state of consciousness.